1 research outputs found
The Multifunctionality of Lanthanum–Strontium Cobaltite Nanopowder: High-Pressure Magnetic Studies and Excellent Electrocatalytic Properties for OER
Simultaneous study of magnetic and electrocatalytic properties
of cobaltites under extreme conditions expands the understanding of
physical and chemical processes proceeding in them with the possibility
of their further practical application. Therefore, La0.6Sr0.4CoO3 (LSCO) nanopowders were synthesized
at different annealing temperatures tann = 850–900 °C, and their multifunctional properties were
studied comprehensively. As tann increases,
the rhombohedral perovskite structure of the LSCO becomes more single-phase,
whereas the average particle size and dispersion grow. Co3+ and Co4+ are the major components. It has been found
that LSCO-900 shows two main Curie temperatures, TC1 and TC2, associated with
a particle size distribution. As pressure P increases,
average ⟨TC1⟩ and ⟨TC2⟩ increase from 253 and 175 K under
ambient pressure to 268 and 180 K under P = 0.8 GPa,
respectively. The increment of ⟨dTC/dP⟩ for the smaller and bigger particles
is sufficiently high and equals 10 and 13 K/GPa, respectively. The
magnetocaloric effect in the LSCO-900 nanopowder demonstrates an extremely
wide peak δTfwhm > 50 K that
can
be used as one of the composite components, expanding its working
temperature window. Moreover, all LSCO samples showed excellent electrocatalytic
performance for the oxygen evolution reaction (OER) process (overpotentials
of only 265–285 mV at a current density of 10 mA cm–2) with minimal η10 for LSCO-900. Based on the experimental
data, it was concluded that the formation of a dense amorphous layer
on the surface of the particles ensures high stability as a catalyst
(at least 24 h) during electrolysis in 1 M KOH electrolyte